Unify Windows client bootstrap and discover network paths

scripts/Install-SguAzureP2sClient.ps1

@@ -65,7 +65,9 @@ try {
         if ($existingConnection) {
             Remove-VpnConnection -Name $ConnectionName -AllUserConnection -Force
         }
-        Add-VpnConnection `
+        $dnsParameters = @{}
+        if ($DomainName) { $dnsParameters.DnsSuffix = $DomainName }
+        Add-VpnConnection @dnsParameters `
             -Name $ConnectionName `
             -ServerAddress $vpnServer `
             -TunnelType Ikev2 `
@@ -75,22 +77,24 @@ try {
             -EncryptionLevel Required `
             -SplitTunneling `
             -AllUserConnection `
-            -DnsSuffix $DomainName `
             -Force | Out-Null
         foreach ($prefix in $AzureNetworkPrefixes) {
             Add-VpnConnectionRoute -ConnectionName $ConnectionName `
                 -DestinationPrefix $prefix -AllUserConnection -PassThru | Out-Null
         }
 
-        $nrptDisplayName = "SGU Azure P2S DNS - $DomainName"
-        Get-DnsClientNrptRule -ErrorAction SilentlyContinue |
-            Where-Object DisplayName -eq $nrptDisplayName |
-            Remove-DnsClientNrptRule -Force
-        Add-DnsClientNrptRule `
-            -Namespace ".$DomainName" `
-            -NameServers $DomainControllerIPv4Address.IPAddressToString `
-            -DisplayName $nrptDisplayName `
-            -Comment 'Managed by SGU Azure P2S bootstrap; routes only the AD namespace to the domain controller.' | Out-Null
+        # The unified bootstrap can discover the domain after connecting.
+        if ($DomainName) {
+            $nrptDisplayName = "SGU Azure P2S DNS - $DomainName"
+            Get-DnsClientNrptRule -ErrorAction SilentlyContinue |
+                Where-Object DisplayName -eq $nrptDisplayName |
+                Remove-DnsClientNrptRule -Force
+            Add-DnsClientNrptRule `
+                -Namespace ".$DomainName" `
+                -NameServers $DomainControllerIPv4Address.IPAddressToString `
+                -DisplayName $nrptDisplayName `
+                -Comment 'Managed by SGU Azure P2S bootstrap; routes only the AD namespace to the domain controller.' | Out-Null
+        }
     }
 
     if ($Connect) {